Head suspension having gram load change reduction and method of assembly

ABSTRACT

A suspension assembly for a magnetic head reduces isolation forces caused by swaging the suspension to an actuator arm of a disk drive. The suspension is formed with a first end, and a second end having an inner periphery which defines an opening. Tabs extend from the inner periphery into the opening. A base plate with a cylindrical hub is welded to the tabs and the hub extends through the inner periphery. The tabs isolate forces caused when the hub is swaged to the actuator arm.

FIELD OF THE INVENTION

[0001] The invention relates to hard disk drives and in particular tohead suspensions for hard disk drives.

DESCRIPTION OF THE PRIOR ART

[0002] Hard disk drives are used in most personal computers, in massmemory storage systems and in other machines. A typical hard driveincludes an enclosure with at least one disk, a spindle motor and anactuator arm with a magnetic recording head. The motor rotates the disk.As the disk rotates, the actuator arm pivots to pass the recording headover the disk surface to read and write data to the disk.

[0003] The actuator arm has two ends. One end mounts on a pivot bearing.The other end of the actuator arm supports a head suspension, to which amagnetic head is assembled. Typically, the magnetic head is formed withan air bearing surface, and during operation flies closely over the disksurface to enable data signals to be recorded and read.

[0004] Disk rotation creates pressure adjacent to the disk surface,which lifts the suspension and head from the disk surface. Thesuspension is spring loaded to resist the lifting force and urges thehead towards the disk surface. This resistive force is termed the “gramload”. At a desired rotational rate, the gram load and lifting forcesbalance, allowing the head to float a precise distance from the disksurface.

[0005]FIG. 3, for example, shows a known suspension and actuator armassembly. The assembly has a base plate 52, sometimes referred to as anut plate assembly, and a suspension 54. The suspension 54 has acircular opening 56. The base plate 52 has a cylindrical hub 58, whichextends through the opening 56. Welds attach the base plate 52 to theactuator arm end of the suspension 54, locating the hub in the center ofthe opening 56. Typically four or six laser welds are used to attach thebase plate 52 to the suspension 54.

[0006] The suspension 54 is formed from a strip of spring metal havingtwo ends and a bend radius region 55 defined between the ends. Themagnetic head is fixed at one end. The other end attaches to theactuator arm 20 by a process known as swaging. During swaging, swageballs of incremental size swage through the hub 58, expanding the hub 58against the actuator arm 20 to hold the suspension 54 in place withrespect to the actuator arm 20. Stresses caused by the swaging processpropagate from the base plate via the welds to the bend radius region 55of the suspension and affect suspension gram load.

[0007] The swaging process may inconsistently affect the bend radiusregion 55, and other parts of the suspension, changing the gram load ofthe suspension. The magnitude of change in gram load varies, even underclosely regulated manufacturing conditions. In some instances, where thedesired gram load is in the range of 2-3 grams, swaging may cause gramload changes of {fraction (1/2)} gram, or more. Ideally, gram loadchanges should be consistent and predictable during thesuspension/actuator arm assembly process.

[0008] The gram load directly affects disk drive operation. When, forexample, swaging changes the gram load beyond an acceptable range, thehead may not record, or read, data properly. To avoid this problem, thesuspension is reworked during assembly. Where reworking fails, the wholesuspension-actuator arm assembly may have to be de-swaged (removed) anddiscarded. Optimally, the gram load change will be slight andconsistent, and thus the suspension and head assembly will not need tobe reworked or discarded. What is desired is a way to minimizeinconsistency of gram load changes caused during swaging.

SUMMARY OF THE INVENTION

[0009] A suspension for a magnetic head includes a first end, a secondend and a bending radius region defined between the ends. The bendingradius region is configured to preload the suspension. A magnetic headis attached to the first end. Preloading the suspension determines thegram load.

[0010] A base plate is welded to the second end of the suspension. Thebase plate includes a hollow cylindrical hub. The second end of thesuspension has an inner periphery defining an opening. The hub insertsthrough the opening to swage the suspension to an actuator arm of a diskdrive. The present invention minimizes stress imposed on the suspensionby the swaging process. This minimization of stress, reduces variabilityand magnitude of gram load changes, which stem from the swaging process.

[0011] According to one aspect of the invention, the inner periphery ofthe suspension includes tabs to minimize force propagation between thebase plate and the suspension by isolating forces caused by swaging.According to another aspect of the invention, multiple isolation weldssurround the inner periphery to isolate forces caused by the swagingprocess. The invention can use tabs of uniform length, or varyinglength. The inner periphery can be generally square, rectangular, orcircular in shape to surround the hub. The tabs are preferably parabolicin shape, being rounded, or triangular and pointed. The isolation-weldscooperate with the tabs to limit force propagation.

BRIEF DESCRIPTION OF THE DRAWING

[0012] The invention will be described in greater detail with referenceto the drawings in which:

[0013]FIG. 1 is an exploded perspective view of a disk drive inaccordance with the present invention.

[0014]FIG. 2 is a perspective view of the actuator arm assembly of FIG.1.

[0015]FIG. 3 is an exploded perspective view of a prior art actuator armand suspension.

[0016]FIG. 4 is an exploded perspective view of the actuator arm, baseplate and suspension in accordance with the present invention.

[0017]FIG. 5 is an exploded perspective view of the assembly of FIG. 4with the base plate welded to the suspension.

[0018] FIGS. 6-14 are top views of alternative embodiments of thesuspension of FIG. 4 in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0019]FIG. 1 shows a disk drive 10 that includes an enclosure 12, a diskspindle motor 14, disks 16, an actuator magnet assembly 18, an actuatorarm 20, a pivot bearing assembly 22, and a suspension assembly 36. Thesuspension assembly 36 supports heads 46, which read from and write datato the disks 16.

[0020] The enclosure 12 has a base 24 and a cover 26. The actuatormagnet assembly 18 mounts on the base 24. The pivot bearing assembly 22mounts the actuator arm 20 on the base 24 in operative proximity to theactuator magnet assembly 18. The cover 26 attaches to the base 24 andseals the enclosure 12.

[0021] The actuator arm 20 has two ends 32 and 34. The suspensionassembly 36 mounts on the end 32 of the actuator arm 20. The diskspindle motor 14 and the disks 16 mount on the base 24 in operativealignment with actuator arm 20. The disk spindle motor 14 rotates thedisks 16 and the actuator arm 20 pivots the suspension assembly 36 toenable the heads 46 to co-act with the disks 16 for transducing datasignals. It can be appreciated that while magnetic heads and diskshaving a magnetically readable surface are used in disk drives, thepresent invention is also useful in conjunction with other deviceshaving, for example, optically readable media and heads.

[0022]FIG. 2 shows the actuator arm 20. The suspension assembly 36includes a suspension 44 and a head 46. The disk 16 has a surface 42.The disk 16 spins in the direction of the arrow 50. The arm 20reciprocates along an arc indicated by the arrows 48. Rotation of thedisk 16 creates air pressure, which lifts the head 46 and floats thehead 46 above the disk surface 42. Flying the head 46 enables the arm 20to pivot without contacting the disk surface 42. In this embodiment,although the head floats, the present invention can be used in deviceshaving a head in contact with a magnetic medium. In any instance, thesuspension 44 precisely regulates gram load.

[0023] The suspension 44 applies a gram load on the head 46 in adirection towards the disk 16, opposing the head 46 lifting force causedby disk 16 rotation. Accordingly, the distance between the head 46 andthe disk surface 42 depends on the gram load applied by the suspension44.

[0024]FIG. 4 shows the actuator arm 20, a base plate 60, the suspension44 and the magnetic head 46. The base plate 60 includes a hub 64. Thesuspension 44 has a first end 70 and a second end 72. The second end 72has an inner periphery 74, which defines an opening 76. The hub 64 hasan outside diameter. The opening 76 is larger than the hub 64 outsidediameter to enable the hub 64 to freely fit through the opening 76.According to one aspect of the invention, the opening 76 diameterexceeds the hub outside diameter, preferably within the range of 0.2 to4.0 mm to isolate force and minimize force propagation from the baseplate to the suspension.

[0025] The inner periphery 74 has tabs 80. The tabs 80 extend radiallyinto the opening 76, defining interstices 86 between each tab 80. Thetabs 80 have a nominal geometry, which does not normally change duringthe swaging process. The interstices 86 are defined between each tab 80to isolate forces, and force propagation, between the base plate 60 andthe suspension 44. The tabs 80 and interstices 86 isolate forces, andforce propagation, between the first end 70 and second end 72 of thesuspension 44. Accordingly, the present invention reduces the degree towhich, swaging affects gram load and minimizes undesired gram loadvariability between actuator arm assemblages during swaging.

[0026]FIG. 5 shows the actuator arm 20 and suspension 44 of FIG. 4. Thebase plate 60 welds to the second end 72 of the suspension 44 at welds82. The hub 64 includes a hollow cylinder, which extends through theopening 76. The actuator arm 20 includes an exactly circular opening 84sized to enable the hub 64 to swage to the actuator arm 20 opening 84.

[0027] During swaging, the hub 64 extends through the opening 84. Swageballs of incrementally increasing diameter press through the hub, andpress the hub 64 outside diameter against the edges of the opening 84 tohold the suspension 44 with respect to the actuator arm 20. The tabs 80of the suspension 44 partially surround the hub 64, isolating forcesfrom the hub 64 and inhibiting propagation of forces form the hub to thesuspension 44 particularly to the bend radius region 55.

[0028]FIG. 6 shows a view of one embodiment of the suspension 44. Thesuspension includes multiple tabs 80 extending from the inner periphery74. The tabs 80 are uniform in length and are generally parabolic inshape. The tabs 80 are integrally formed with the suspension 44.

[0029] The suspension 44 includes four welds 82 arranged in a squareconfiguration surrounding the inner periphery 74. The interstices 86 andtabs 80 intersect distances between adjacent welds 82. To illustrate,one interstice 86 and one tab 80 intersects the line 88, which is drawnbetween adjacent welds 82. In an alternate embodiment of the invention,the interstice 86 and tab 80 bisect the distance between adjacent welds82. In another variation of the invention, multiple tabs 80 andinterstices 86 intersect the distance between adjacent welds.

[0030]FIG. 7 shows a view of one embodiment of the suspension 44. Thewelds 82 are defined on each tab 80. The tabs 80 are generallytriangular in shape and pointed radially inward towards the center ofthe opening 76. The opening 76 surrounds the rim of the hub 64.

[0031]FIG. 8 shows the suspension having a generally square innerperiphery 74 defining the opening 76. The inner periphery 74 has fourcorner regions 90. The tabs 80 are generally parabolic in shape andextend from each of the corner regions 90. Each tab 90 includes one weld82. The inner periphery 74 has four sides. Each side has a weld 82.

[0032]FIG. 9 shows the suspension 44. The tabs 80 interconnect, forminga second inner periphery 92. The tabs 80 define three arcuate openings94 adjacent the second inner periphery 92, and between the second innerperiphery 92 and the inner periphery 74. Each tab includes a pair ofwelds 82 in radial alignment with respect to the axis of the opening 76.A weld 82 is positioned between the inner periphery 74 and each arcuateopening 94.

[0033]FIG. 10 shows the suspension 44 having a generally square innerperiphery 74 having four corners 90. The tabs 80 extend from each of thecorners 90. The suspension 44 has welds 82 on each tab 80. The welds 82are paired in radial alignment with respect to the cylindrical hub 64.The welds 82 are located on each tab, or every other tab, according tothe particular tab and weld design. The welds 82 radially align toisolate force caused by swaging. The tabs 80 include a neck region 105and a generally diamond shaped end 107. The neck region 105 cooperateswith the welds to isolate forces caused by swaging. The diamond-shapedend enables the base plate to form a solid weld to the tab 80. It can beappreciated that although a diamond-shaped end 107 is shown, a spaded orrounded shaped end can be readily welded to the base plate (FIG. 5).

[0034]FIG. 11 shows a suspension for a magnetic head including a stripof force isolation elements 100, which extend across a portion of thesuspension 44 to isolate the second end 72 from the first end 70.According to one aspect of the invention, the force isolation elements100 include multiple isolation welds 102 aligned in parallel andextending linearly across the suspension 44.

[0035] The suspension 44 includes a bend radius region 101 forregulating gram load. The welds 102 extend adjacent the bend radiusregion 101, between the bend radius region 101 and the inner periphery74. According to one aspect of the invention, the welds cross a portionof the suspension, adjacent the hub 64. In an alternate embodiment, thewelds 102 extend fully across the suspension 44. The strip of forceisolation features 100 extends across the suspension 44 to minimizestress communicated form the base plate, to the bend radius region 101.

[0036]FIG. 12 shows a suspension 44 having a first end 70 and a secondend 72. The inner periphery 74 is defined at the second end 72. Thesuspension 44 includes a strip of isolation welds 102 encircling the hub64 to isolate force and to minimize propagation of force between thesecond end 72 and the first end 70. Preferably, 8-16 laser welds 102encircle the hub 64.

[0037]FIG. 13 shows the inner periphery 74 having a generally squarecross-section and four corners 106. The inner periphery 74 defines anarea larger than the area defined by the hub 64. The welds 82 standadjacent each corner 106 of the inner periphery 74.

[0038]FIG. 14 shows the suspension 44. The suspension 44 has an innerperiphery 74 with sides 108 and corners 90, and eight tabs 80 ofnon-uniform length. The tabs 80 extend from the sides 108 and corners90. The tabs 80 extending from the corners 90 are longer than the tabs80 extending from the sides 108. Each tab 80 extending from the corners90 has a weld 102 to attach the suspension 44 to the base plate (FIG.5). Accordingly, every other tab 80 includes a weld 102.

[0039] By virtue of this invention, a head suspension is swaged to anactuator arm of a disk drive so that suspension gram load changesnormally associated with the swaging process are significantly reduced.The method includes providing a suspension with two ends, an innerperiphery at one end, and a magnetic recording head at the other end,and tabs that extend from the inner periphery. The tabs defineinterstices between each tab which enable the tabs to absorb forces.

[0040] The novel assembly provides a base plate with a hub welds to eachof the tabs, or every other tab. While the base plate welds to the tabs,additional welds can attach the base plate to other regions of thesuspension, adjacent the inner periphery. Alternatively, the welds canbe between the tabs.

[0041] The hub extends through the inner periphery of the suspension toenable the suspension to swage to the actuator arm. The actuator arm hasan opening. The hub extends through the actuator arm opening. Swageballs, in increasing size, press through the hub to attach thesuspension to the actuator arm. The tabs are configured in selectedshapes to absorb forces, and thereby reduce suspension gram load changesdeveloped during the swaging process.

What is claimed is:
 1. An assembly for use in a disk drive comprising: asuspension having a first end and a second end, said second end havingan inner periphery defining an opening; a magnetic head attached to saidfirst end for transducing data signals; and a plurality of tabs attachedto the inner periphery, said tabs extending into said opening.
 2. Anassembly as set forth in claim 1 including a base plate having a hub,wherein the base plate is welded to said tabs to isolate forces betweenthe base plate and the suspension.
 3. An assembly as set forth in claim1, wherein the tabs are parabolic in shape.
 4. An assembly as set forthin claim 1, wherein the tabs are pointed.
 5. An assembly as set forth inclaim 1, wherein the tabs interconnect.
 6. An assembly as set forth inclaim 6, wherein the interconnected tabs form arcuate openings.
 7. Anassembly as set forth in claim 1, wherein the inner periphery has fourcorners, and wherein one tab extends from each of the corners.
 8. Anassembly as set forth in claim 1, wherein the inner periphery has foursides, and wherein one tab extends from each of the sides.
 9. Anassembly as set forth in claim 1, wherein the tabs are uniform inlength.
 10. An assembly as set forth in claim 1, wherein the tabs varyin length.
 11. An assembly as set forth in claim 1, wherein the innerperiphery has four sides and four corners, and tabs extending from eachof the sides and each of the corners, and wherein the tabs extendingfrom the corners are longer than the tabs extending from the sides. 12.An assembly as set forth in claim 1, wherein the inner periphery isgenerally rectangular in shape.
 13. A method of swaging a head assemblyto an actuator arm of a disk drive for reducing assembly gram loadchanges, comprising the steps of: providing a suspension with an innerperiphery and tabs extending from the inner periphery; welding a baseplate with a hub to the suspension and extending the hub through theinner periphery of the suspension; providing an actuator arm with anopening; extending the hub through the actuator arm opening; and swagingthe suspension to the actuator arm.
 14. A method as set forth in claim13, wherein the step of welding a base plate includes welding the baseplate to at least one tab.
 15. A method as set forth in claim 13,wherein the step of welding a base plate includes welding the base plateto each of the tabs.
 16. A magnetic head assembly comprising: a headsuspension having a first end and a second end, the second end having aninner periphery defining an opening; a magnetic head attached to thefirst end for transducing data signals; a base plate having a hub, thebase plate being welded to the second end, wherein the hub extendsthrough the inner periphery; a strip of force isolationelements(extending across a portion of the suspension to isolate forcesimposed on the suspension by the base plate.
 17. An assembly as setforth in claim 16, wherein the force isolation elements include a stripof isolation welds.
 18. An assembly as set forth in claim 17, whereinthe strip of welds extends linearly across the suspension.
 19. Anassembly as set forth in claim 17, wherein the suspension includes abend radius region, and said strip of welds extends across thesuspension between the bend radius region and the inner periphery. 20.An assembly as set forth in claim 17, wherein said strip of isolationwelds encircle the hub to weld the base plate to the second end.
 21. Anassembly as set forth in claim 16, wherein said a strip of forceisolation welds attach the base plate to the second end, and wherein thewelds align radially from the hub.
 22. A disk drive comprising: anenclosure having a disk motor; disks rotatably mounted on the diskmotor; an actuator arm attached in the enclosure; and a suspension for amagnetic head, the suspension being attached to the actuator arm,wherein the suspension includes a first end and a second end having aninner periphery and tabs, wherein the inner periphery defines anopening, and wherein the tabs attach to the inner periphery and extendinto the opening.
 23. A disk drive as set forth in claim 22, wherein thesuspension includes a base plate, and each tab includes a forceisolation weld to attach the base plate to the suspension.
 24. A diskdrive as set forth in claim 22, wherein the suspension includes a baseplate, and alternate tabs include a force isolation weld to attach thebase plate to the suspension.
 25. A disk drive as set forth in claim 22,wherein the suspension includes a base plate and force isolation weldswhich surround the inner periphery to attach the base plate to thesuspension, and wherein the tabs define interstices which intersectdistances between adjacent welds.